The present disclosure relates to a light-emitting element, a manufacturing method thereof, and a display device including the light-emitting element.
For example, a so-called laser display device, that is, a display device referred to as a projector device, which includes a light-emitting element made from a semiconductor laser element as a light source, is well known from, for example, Japanese Unexamined Patent Application Publication No. 2009-025462. A laser display device has features of small size, light weight, and low power consumption in addition to high brightness and high definition, thereby attracting a lot of attention. However, in the laser display device, speckle noise becomes a factor which deteriorates an image quality of an image and a video. Speckle noise is a phenomenon that results from interference of scattered light on a laser irradiated surface displaying an image and a video such as a screen, a wall, and the like due to high coherence of a laser beam, and is caused by a presence of fine concavities and convexities on the laser irradiated surface.
A super luminescent diode (SLD) which has a structure similar to a semiconductor laser element, expands a spectrum width by suppressing a laser oscillation, and reduces coherence is attracting attention. The super luminescent diode has high directivity at the same level as a laser beam, and furthermore is a light-emitting element which can have a light spectrum as wide as a general light-emitting diode (LED).
For example, in Japanese Unexamined Patent Application Publication No. 2-310975, a super luminescent diode in which an end surface embedded region and a non-excitation region are formed in a vicinity of the light-emitting end surface by having a direction, in which a waveguide extends, perpendicular to a light-emitting end surface is disclosed as the related art in FIG. 3, a super luminescent diode with an oblique waveguide is disclosed in FIG. 4, and furthermore, problems of the super luminescent diode having these structures are indicated. Then, in order to solve these problems, by making the waveguide curved, a coupling coefficient of light to a waveguide is suppressed and induced emission is suppressed, thereby expanding a spectrum width.